This invention relates to flexible storage media cartridges and, more particularly, to such cartridges which contain a drive member in permanent engagement with the media for driving the media while permitting the media to be self-leveling within the cartridge housing.
This invention further relates to copending U.S. patent application Ser. Nos. 848,181, 848,182, and 848,184, filed of even date with and assigned to the assignee of the present invention. Copending application Ser. No. 848,181, now abandoned, describes a cartridge containing a flexible storage media. A cylindrical chamber is provided therein to retain the storage media and a cavity in the cylindrical wall of the chamber provides back pressure on the media to stabilize contact with a recording and/or playback head for recording or reading information onto the media. Copending Application Ser. No. 848,182 describes a recording system comprising a flexible information storage media which rotates above a smoothing plane surface. A flexible spring member biases the storage media against a recording and/or playback head for recording or reading information onto the media. Application Ser. No. 848,184, now abandoned, describes a cartridge containing a flexible information storage media which is coupled to a drive member by means of at least one pin member from the drive member extending through at least one opening in the storage media. The storage media is free to move laterally with respect to the drive member.
In recording or reading information on a moving information storage media, such as magnetic recording, relative motion between the record/read head and the recording media is required. The relative velocity between the head and media interface may be, for example, 550 IPS for video and high density digital applications. To achieve maximum performance, there must be an interface of intimate contact between the record/read head and the media surface without destruction or excessive wear of the magnetic flux responsive coating on the surface.
As contact pressure between the head and media is increased to improve performance, both media and head wear are increased. The problem is particularly severe in video applications, and compounded where the media is utilized for storing single video frames on separate tracks of a magnetic disc wherein one track at a time is continuously in contact with the head to provide a continuous stationary display of a single frame. In only five minutes of play time revolving at 3600 RPM, for example, a track on the disc is scraped about 18,000 times by the head. The wear products are so hard and abrasive that they are commonly used as lapping compounds.
To prevent failure causes by contact between the head and disc, lubricated surfaces and/or air film separations have been used. However, any separation between the head and disc caused by such lubricating fluid or air film imposes a loss of signal and, hence, performance. A head/disc separation equal to one wavelength could cause about a 54.6-dB loss in the output of the replay head. Since it is desired to record wavelengths that approach 70.mu.", the playback head voltage is reduced to 50% by only 7.7.mu." of separation. On the otherhand, as discussed above, reduction of separation to meet desired performance would cause the interface to be destroyed within a few seconds.
Prior art solutions to the head-to-disc interface problem have generally been of two types: flying heads in conjunction with rigid hard plated discs, and heads having large surface areas buried in soft flexible "floppy" discs. Flying head discs are very expensive and require complicated and expensive recording/playback systems. The flexible or so-called "floppy" disc reduces the handling and cost problems realized in the flying head rigid-disc system. Some record/read heads for "floppy" discs are relatively large to provide an interface comprised of the large contoured head buried in the soft flexible media. The large record/read head surface area distributed the force per unit area to reduce media wear and separation loss. As the media is moved past the head, however, air collects between the head and disc surface to form an air film. The thickness of this air film is a function of media tension, head surface radius, viscosity of the air, and disc head relative velocity. Because of these restraints, most flexible or "floppy" disc applications are limited to slow speed, low bandwidth digital computer applications or voice recording systems. The performance penality realized precluded the use of such flexible or disc interface for high-speed wide-bandwidth or video-type applications.
In U.S. Pat. No. 4,069,508, a system is described in which a flexible disc is rotated over a stationary smoothing plane surface by means of a drive member permanently connected to a rotational means. The drive member includes at least one pin member which mates with at least one opening in the storage media for coupling the information storage media thereto with the at least one opening having a larger perimeter than the at least one pin member to the extent that the information storage media is freely laterally moveable along the pin member wherein an air cushion of predetermined thickness is formed between the stationary surface and storage media when the media is in rotation. In such allowed patent application, several cartridge embodiments are described in which the drive member is permanently connected to the drive shaft of the rotational means, and is introduced into a centrally-located opening in the bottom smoothing plane surface of the cartridge for direct engagement with the disc or the entire smoothing plane surface is separate from the cartridge. Some problems which may be encountered with such cartridge include: difficulty encountered in mating the openings in the flexible storage media with the pins located on the drive member, and secondly, difficulty encountered is positioning a disc recorded on one recording apparatus for playback on a second recording apparatus in which the pins on the drive member or the openings in the disc are imprecisely located.
It is therefore an object of the present invention to provide an improved technique for storing information on a flexible storage media.
Another object of the invention is to provide an improved system for magnetically storing information on a flexible magnetic recording disc.
A still further object of the invention is to provide a flexible magnetic storage disc cartridge which permits a high-performance, narrow-track video record head to be used in contact with the magnetic disc.
It is another object of the invention to provide an apparatus which permits the precise recording and reproducing of wide bandwidth signals such as video signals using inexpensive flexible particulate-type recording media cartridges.
Another object of the invention is to provide a continuously replayable flexible magnetic storage media cartridge in which an air bearing of preselecting thickness between the replay head and media is maintainable regardless of head loading.
A further object of the invention is to provide a cartridge containing a recording media with a compliant, but resilient, magnetic recording surface capable of withstanding shock, vibration and head crashes without media degradation.
A still further object of the invention is to provide the stable record or playback of a flexible information storage media while it is in rotation in any plane, including upside-down.
It is another object of the invention to provide a cartridge for a flexible magnetic storage disc which is easily coupleable to a drive motor.
Yet a further object of the invention is to provide a flexible disc cartridge which may be accurately recorded and played back in different apparatus.